#include <stdio.h>
#include <stdlib.h>
int main()
{
    int *a = (int *)malloc(sizeof(int));
    *a = 4;
    printf("a:%p\n", a);
    {
        free(a);
        int *b = (int *)malloc(sizeof(int));
        printf("a:%p\n", a);
        printf("b:%p\n", b);
    }
    printf("%d\n", *a);
}
